Extensions of the strip-yield model concerning different influencing factors on fatigue crack growth

The strip-yield model is a common tool to calculate the cyclic crack tip opening displacement and the fatigue crack growth life of structures in case of isothermal fatigue loading. As part of an extension of the model the rheological Masing model consisting of spring-slider elements connected in parallel is used to describe the material's stress-strain curve. For this purpose, different yield stresses are allocated to the numerous sliding frictional elements. Instead of the usually applied constant yield stress, these different yield stresses are assigned to the elements into which the crack ligament line is divided. Afterwards, these elements are randomly arranged along the crack ligament line. Besides an improved modelling of the mechanical material behavior the consideration of microstructural aspects of fatigue crack growth becomes possible by influencing the values of the yield stresses near the crack initiation site.